• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.641-652
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• 2005

In this paper, the Coefficient of Subgrade Reaction was analyzed from the data which were the results of lateral pile loading tests and pressuremeter tests on construction sites. The prediction method with N-value was compared with lateral pile loading tests and the results of lateral pile loading tests were compared with the prediction method considering diameter of a pile. Also, the results of lateral pressuremeter tests were compared with those of lateral pile loading tests. As a result, consideration for a diameter and lateral deformation of a pile was needed when the coefficient of horizontal subgrade reaction is presumed. Therefore, a formula which is taking into account the allowable deformation of a pile was suggested from lateral pressuremeter tests in this study.

• Journal of the Korean Geotechnical Society
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• v.24 no.6
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• pp.57-67
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• 2008

Two test methods, nonrepetitive plate loading test (NPLT) and repetitive plate loading test (RPLT) are being used to control the quality of compaction through the evaluation of the stiffness of subgrade soils in the Korea railway industry. Subgrade reaction modulus ($k_{30}$) from the NPLT and strain modulus ($E_v$) from the RPLT are the index values to check them. The methods have similar aspects, but they differ in the modulus evaluation method, the numbers of loading stage, termination procedures, etc. This paper analyses the differences of the two test methods and evaluates the relationship between subgrade reaction modulus and strain modulus. In order to develop the relationship, total 22 tests were performed including the NPLT and the RPLT at the 6 original grounds, and 5 upper or lower subgrades in Kyungbu High Speed Railway II stage construction sites. According to the soil conditions, the relationship between subgrade reaction modulus and strain modulus was proposed with corrections by considering strain states, mean confining pressures, and Poisson's ratio.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.253-254
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• 2014

In offshore, various external forces such as wind force, wave force and impulsive breaking wave force act on offshore structures. Many researches about this forces are published. Kim and Cao(2008) published researche on wave force of vertical cylinder. Kim and Go(2013) performed research on the subgrade reaction by external forces. Among this forces, impulsive breaking force is more massive than other forces, especially. Therefore, the studies about impulsive breaking wave forces have been carried out. Chun and Shim(1999) analyzed dynamic behavior of cylindrical pile subjected to impulsive breaking wave force. In this study, when the impulsive breaking wave force acts on the offshore wind turbine, the subgrade reaction acting on the mono-pile of the offshore wind turbine is calculated by p-y curve. The calculation is carried out to the multi-layered.

• Geomechanics and Engineering
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• v.7 no.6
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• pp.679-703
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• 2014

This paper investigates nonlinear response of 51 laterally loaded rigid piles in sand. Measured response of each pile test was used to deduce input parameters of modulus of subgrade reaction and the gradient of the linear limiting force profile using elastic-plastic solutions. Normalised load - displacement and/or moment - rotation curves and in some cases bending moment and displacement distributions with depth are provided for all the pile tests, to show the effect of load eccentricity on the nonlinear pile response and pile capacity. The values of modulus of subgrade reaction and the gradient of the linear limiting force profile may be used in the design of laterally loaded rigid piles in sand.

• Journal of Ocean Engineering and Technology
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• v.13 no.1 s.31
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• pp.94-104
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• 1999

In order to evaluate the performance of axially of laterally loaded piles experimentaly, pile load tests can be carried out at the site Otherwise stress analyses or subgrade reaction analyses can solve the problem. In this study, stress analysis using FLAC code and subgrade reaction analyses using load transfer curves recommended by API(1993) were performed consistently on the basis of a result of site investigations, and the result of analyses was compared with the measured. As a result the behavior of pile heads was analyzed accurately for both axially and laterally loaded tests. Furthermore axially transferred loads were calculated appropriately for the measured and axial loads were transferred mainly mainly by the frictional resistance rather than by the tip resistance. Consequently, it can be commented that both analysis methods of soil-pile systems are applicable at teh objective site and that solutions may be more accurate if material properties from the site investigation are more explicit.

• International Journal of Highway Engineering
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• v.16 no.6
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• pp.69-78
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• 2014

PURPOSES : The purpose of this paper is showing that the state of pavement sublayers can be evaluated differently according to direction of FWD. METHODS : The concrete pavement slabs above subgrade without anything, subgrade with cavity, and box culvert were modeled by finite element method(FEM). The modeled pavements were analyzed by changing the direction of falling weight deflectometer(FWD). The deflection results obtained from FEM were used to calculate radius of relative stiffness and composite modulus of subgrade reaction using AREA method. Then, the analyzed results were compared to the results of the test performed at the Korea Expressway Corporation(KEC) test road. RESULTS : The composite modulus of subgrade reaction increased with subgrade elastic modulus, while radius of relative stiffness decreased. The pavement sections of pure earth showed the consistent results regardless of FWD direction. In case there was cavity, the radius of relative stiffness was larger and composite modulus of subgrade reaction was smaller when FWD was leaving the cavity than when approaching the cavity. This pattern became clear when the cavity got larger. In case of the section with box culvert, the pattern was opposite to the case of cavity. When the soil cover depth increased, the effect of box culvert got smaller. When the load was applied far from the cavity and box culvert, the effect was also declined. The test performed at the KEC test road showed identical results to those of finite element analysis. CONCLUSIONS : The direction of FWD should be considered in evaluation of the state of pavement sublayers because it can be evaluated differently even under identical condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.267-274
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• 2021

Among several methods for determining the allowable lateral resistances of piles, the subgrade reaction method and ultimate lateral resistance method are generally used. To determine the effects of the soil conditions, pile head restraint conditions, and pile lengths on determining the allowable lateral resistances of piles, computations of the allowable lateral resistances of piles using the two methods were executed, and the computation results were compared. For piles in soft cohesive soil, the pile design is governed by the allowable lateral resistance of a pile from subgrade soil reaction method regardless of the pile head restraints conditions and pile lengths. The allowable lateral resistance of a pile from the ultimate lateral resistance governs the design as the undrained shear strength increases. Except for the case of a short pile, which is installed in loose granular soil, the allowable lateral resistance of a pile from ultimate lateral resistance governs the design of laterally loaded piles. According to this study, computation of the ultimate lateral resistance of a pile is needed, even though some opinions suggest that the design of a laterally loaded pile is satisfied only by the subgrade reaction method. The pile width barely influences the coefficient of horizontal subgrade reaction. Realistically, the effect of the pile width can be disregarded in the condition of common pile widths of 20~90cm.

• Geotechnical Engineering
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• v.1 no.2
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• pp.75-80
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• 1985

For the analysis of contineous building foundation, the conventional methods assume that subgrade reaction is uniform. But for more accurate analysis, the method considering variable distribution of subgrade reaction and the conventional methods were compared. Addithionally pontoon foundation to reduce the stress of foundation is introduced.

• Proceedings of the Korean Geotechical Society Conference
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• 1996.10a
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• pp.107-114
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• 1996

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1827-1832
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• 2007

The purpose of a railway track is to provide a smooth surface for safe and economical train transportation. The performance of the track results from a complex interaction of the track and subgrade components in response to train loading and environmental actions. In the past, the role of subgrade as the track foundation were not recognized adequately. There are insufficient information and inadequate methods for subgrade design, assessment and improvement. This situation has survived for a long time largely because a subgrade defect can often be adjusted by adding more ballast under the ties or applying more frequent track maintenance. Therefore, the application of reinforced roadbed technology will be expected to increase in the future. The reinforced roadbed thickness is set depending on subgrade reaction modulus$(K_{30})$ in the condition of upper subgrade through PBT in both conventional railroad and KTX railroads. As train velocity (V), train passing tonnage (N), and train axial load (P) are not considered in design, the roadbed thickness could be overestimated (or underestimated). Therefore, In this study, the computer model, GEOTRACK, was analyzed the influence of reinforced roadbed thickness factors on track modulus and the characteristics of stress pulses in track and subgrade generated by repeated axle loading.